"instmsg2" => "MailPictures is now installed in : $installfolder\n"
."Nautilus action configuration is done\n"
."A symbolic link has been created in nautilus-scripts folder.\n"
."\n"
."WARNING :\n"
."1. A small nautilus-actions bug prevent manual deleting "
."of this application. The best way is to use the <b>uninstall.pl</b> script. "
."You can delete all other files, but please keep this script..."
."2. Nautilus-actions installation needs nautilus to be restart, "
."it can be done logging out your session.\n"
."\n"
."<b> Thanks to report bug to razerraz-AT-free.fr </b>",

"uninstmsg2" => "MailPictures has been deleted, $installfolder doesn't exist anymore\n"
."Symbolic link has been deleted in nautilus-scripts folder.\n"
."Nautilus-actions installation has been deleted, think to log out "
."in order to restart nautilus\n"
."<b>Thanks to have test this program</b>");
Thanks a lot in advance

I gave it a whirl as well.
Translated and rephrased some lines to give it a better feel in Dutch.
But without handson experience with your application it can never be perfect, I think this is a good start tho

You might have to fix the layout in some places if the lines dont really fit, but I doubt that will be much of a problem.
It might also be a good idea to have your English checked by a native speaker, since it contains some errors as well. I could also point some out but perhaps a native speaker would do a better job at that.
Good luck!_________________Getting there... one way or another